The invention is in the field of optical communication.
Optical communication networks include network elements with plug-in boards offering different degrees of functionality and ranging from optical repeaters for merely transponding an optical signal to optical transponders capable of both transponding an optical signal and performance monitoring. Optical repeaters can transpond different optical signals both in terms of transmission protocol and bit rate, namely, the same optical repeater can transpond inter alia SDH at different rates, ATM at different rates, PDH at different rates, and others. Against this, an optical transponder transponds and performance monitors a single optical signal i.e. a specific transmission protocol at a specific bit rate. The plug-in boards are periodically replaced for maintenance purposes, and, in the case of optical transponders, as the need may arise to support new system configurations.
In accordance with a first aspect of the present invention, there is provided an optical transponder comprising an optical/electrical (O/E) receiver module for converting an ingressing optical signal from an optical signal source to an electrical signal; a performance monitoring module for effecting performance monitoring on said electrical signal, an electrical/optical (E/O) transmitter module for regenerating an egressing optical signal from said electrical signal for feeding to an optical signal destination, and wherein said performance monitoring module is capable of effecting performance monitoring on the electrical signal equivalents of at least two different optical signal types each uniquely identifiable in terms of transmission protocol and/or bit rate.
The first aspect of the present invention is directed toward providing an optical transponder capable of supporting performance monitoring (PM) of at least two different optical signal types, thereby increasing its deployment flexibility and facilitating inventory reduction. An optical transponder of the present invention preferably supports performance monitoring of optical signals of different transmission protocols at one or more different bit rates. To be updated with the optical signal type of an ingressing optical signal, an optical transponder of the present invention can either be externally configurable by way of a network management system, or self-configurable if provided with a reference pattern spotting scheme for automatic optical signal type identification. An optical transponder of the present invention preferably supports so-called 3R regeneration of optical signals as opposed to so-called 2R regeneration, namely, re-timing of optical signals in addition to their re-shaping and re-amplification.
In accordance with a second aspect of the present invention, there is provided an automatic optical signal type identification method comprising the steps of:
(a) converting an optical signal into an electrical signal;
(b) storing a reference pattern dictionary with a plurality of reference, patterns each uniquely identifying a different optical signal type; and
(c) spotting a reference pattern embedded in the electrical signal for identifying the optical signal type of the optical signal.
The second aspect of the present invention is based on the fact that each optical signal type has a unique reference pattern in terms of a feature vector, and either a fixed or variable byte length between a pair of immediately consecutive occurrences of its feature vector, thereby enabling its identification from other optical signal types. The automatic optical signal type identification method of the present invention preferably identifies optical signal types ranked by ascending byte length between immediately consecutive occurrences of feature vectors. The automatic optical signal type identification method of the present invention can identify an optical signal type of an optical signal either off-line or on-line from its equivalent electrical signal.